Pilot of crashed Asiana plane was in 777 training(2)

Hersman said it was too early to speculate on the cause of the crash. The data recorders corroborated witness accounts and an amateur video, shown by CNN, that indicated the plane came in too low, lifted its nose in an attempt to gain altitude, and then bounced violently along the tarmac after the rear of the aircraft clipped a seawall at the approach to the runway.

Asked whether the information reviewed by the NTSB showed pilot error in the crash, Hersman did not answer directly.

"What I will tell you is that the NTSB conducts very thorough investigations. We will not reach a determination of probable cause in the first few days that we're on an accident scene," she told reporters.

Asiana said mechanical failure did not appear to be a factor. Hersman confirmed that a part of the airport's instrument-landing system was offline on Saturday as part of a scheduled runway construction project, but cautioned against drawing conclusions from that.

"You do not need instruments to get into the airport," she said, noting that the weather was good at the time of the crash and the plane had been cleared for a visual approach.

The Asiana flight was flying to San Francisco from Seoul with 291 passengers and 16 crew members on board. Several large groups of Chinese students were among the passengers.

The passengers included 141 Chinese, 77 South Koreans, 64 Americans, three Indians, three Canadians, one French, one Vietnamese and one Japanese citizen.

SERIOUS INTERIOR DAMAGE

People on the flight said nothing seemed amiss until moments before the crash. Pictures taken by survivors showed passengers hurrying out of the wrecked plane, some on evacuation slides. Thick smoke billowed from the fuselage and TV footage showed the aircraft gutted by fire. Much of its roof was gone.

Interior damage to the plane also was extreme, Hersman said on CNN earlier on Sunday.

"You can see the devastation from the outside of the aircraft, the burn-through, the damage to the external fuselage," she said. "But what you can't see is the damage internally. That is really striking."

The NTSB released photos showing the wrecked interior cabin with oxygen masks dangling from the ceiling.

Hersman said the first emergency workers to arrive at the scene included 23 people in nine vehicles. San Francisco Mayor Ed Lee said a total of 225 first responders were involved.

"As chaotic as the site was yesterday, I think a number of miracles occurred to save many more lives," Lee said at the airport news conference. Appearing later at San Francisco General Hospital, he declined to address whether one of the Chinese teenagers may have been run over.

It was the first fatal commercial airline accident in the United States since a regional plane operated by Colgan Air crashed in New York in 2009.

Asiana, South Korea's junior carrier, has had two other fatal crashes in its 25-year history.

Agencies